Answer:
2 / 7
Step-by-step explanation:
Coin flipped 3 times has following outcomes, of heads 'H' & Tails 'T'
HHH , TTT , HTT, THT , TTH , THH , HTH , HHT = total outcomes
P (A) = 2 consecutive heads , P (B) = atleast one tail
P (A) = 2 outcomes ( HHH , HHT , THH ) / total 8 outcomes = 3 / 8
P (B) = 7 outcomes (all except HHH) / total 8 outcomes = 7 / 8
P (A | B) = P ( A ∩ B ) / P (B)
P ( A ∩ B ) = P ( 2 consecutive heads & atleast one tail) / Total outcomes = 2 outcomes ( HHT , THH ) / total 8 outcomes = 2 / 8
So, P (A | B) = ( 2 / 8 ) / ( 7 / 8 ) = 2 / 7
